The state of the art telecommunications systems know for some time the home or office zone concept. Here a mobile phone of which the current location is inside a predefined zone (in practise one or more cells of a HPLMN) is treated differently then when it is outside such a zone. Most commonly the charges are lower when calling inside the zone. This is comparable to local calls in a fixed network. The related call completion, when such a mobile phone is called, consists of just connecting when the called party is in its zone or connecting to the voice mail when outside the zone. More advanced is to give the calling party the freedom to select a “connect anyway” option with a higher charge rate. FIG. 1 gives an overview of the state of the art system.
An incoming call A for the mobile phone arrives at the MSC (Mobile services Switching Centre) in the HPLMN (Home Public Land mobile network) of the mobile phone. This MSC is also known by its designation as G-MSC (Gateway MSC) to make a difference to a terminating MSC (T-MSC) when the mobile phone is in another PLMN than the HPLMN. First act of the MSC is to obtain via an interface 4 to the HLR (Home location Register) the subscriber data stored in the HLR. Based on a set parameter T-CSI (terminating CAMEL subscription information) in the subscriber data or by detecting a zone related mobile number in number analysis, the MSC invokes the zone application C in the SCP (Service Control Point) by means of a CAP-IDP message (CAMEL Application Part—Initial Detection Point). The zone application checks on the location of the mobile phone. It therefore can do a MAP-ATI (Mobile Application Part—Any Time Interrogation) via an interface 3 to the HLR. This will provide amongst others the last stored position of the mobile phone. Detailed position information is however not regular updated in the HLR. The HLR stored position is time stamped so the age can be determined. Instead of MAP-ATI, the zone application can send a MAP-ALR (Mobile Application Part—Active Location Request) via the interface 3 to the HLR. Now the HLR does a position request via the interface 4 to the T-MSC. The T-MSC replies with a position report via the interface 4. In FIG. 1 the situation is given where the mobile phone resides in the HPLMN and therefore G-MSC and T-MSC are the same. The position report is stored with the time stamp in the HLR and can be accessed by a next MAP-ATI. As the zone application did an MAP-ALR, the HLR provides the position report via the interface 3 to the zone application.
The position information in the report comprises several elements;                MCC—Mobile Country Code (country the mobile is currently,        MNC—Mobile Network Code (PLMN serving the mobile),        LAC—Location Area Code (PLMN is divided into LAs),        CI—Cell Identifier (GSM cell mobile is camping),        SAI—Service Area Identifier (UMTS node-B serving the mobile),        LAT/LONG position and uncertainty in that position, Velocity of mobile.        
The elements MCC, MNC and LAC are standard and always provided. CI is only given for GSM phones, SAI only for UMTS phones. The LAT/LONG position and velocity depends on settings in the MSC which can be blocked, free or only available for operator own network nodes. Details on the LAT/LONG position can be found in the 3GPP Technical Specification 23.032. Velocity is only available when velocity measurement is implemented in the MSC.
Instead of the HLR, advanced position reports can also be obtained from a MPS (Mobile Positioning System) via the MAP interface using the MLP protocol when the network is equipped with an MPS. The output is comparable to that provided by the HLR.
A Zone is defined as one or more cells (GSM) or Service areas (UMTS). By default they are all located in the HPLMN. The may reside on the border of the HPLMN or any where else inside the HPLMN. The defined zone may be located across the border of two adjacent Location Areas.
The zone application compares the actual position by means of the MCC, MNC and CGI/SAI value with the defined cells forming the zone. When the mobile is in the zone, connection to the mobile B is ordered, else connection to the voice mail BVM of mobile B is ordered. The order is sent to the MSC with a CAP-CON (CAMEL Application Part—Connect) via the interface 2. The MSC then establishes the connection to either mobile B or its voice mail BVM.
Instead of just connect to the voice mail a more advanced mode is known, where the user may select anyhow connection but with additional charges. In this case first an order is given to the MSC for playing an announcement to the calling party A. The order CAP-PA (CAP-Play Announcement) consists of or a combination of; fixed message identifiers (of pre-recorded messages), text strings (that will be converted to speech) or a variable message identifiers (of pre-recorded message with variable parameters included like time, date, duration or price that are provided with the identifier and converted to speech).
This announcement may include user selectable options so that the calling party can select an option by pressing one of the keys on the phone.
After playing the announcement the MSC returns a CAP-SSR (CAP-Specialized Resource Report) that includes the CAP-PA details. In order to receive the pressed key information from the user the zone application has to send a CAP-PC (CAP-Prompt and Collect user information). The CAP-PC includes number of wanted digits, timeout value etc. The MSC replies with a CAP-PCR (CAP-PC Result) when the digits are entered or after timeout.
The zone server applications acts on the user selection with a CAP-CON to either mobile B or to its voice mail BVM.
Full details on the CAP operations can be found in the CAP technical specification 3GPP TS 29.078
Although FIG. 1 shows an implementation based on a zone server application in a SCP it can be implemented in various other ways like a dedicated zone server node acting towards the MSC as SCP.
The area of a zone is generally rather small compared to the full area of the HPLMN. The information provided to the calling party is therefore limited to; the called party is in a VPLMN, in the HPLMN, or in one of his defined zones. The Location Area (LA), as intermediate area for presence detection is not usable as a zone may have cells in more then one Location Area when it lies across the border of two Location Areas.
The object of the invention is to provide a calling party with more detailed information on a current location of the called party and a wider choice of related call completion options.